This pilot study aims to gather preliminary evidence on how different hemoglobin levels impact blood biomarkers related to bleeding. The feasibility of conducting a future larger clinical trial will also be assessed. Red blood cell transfusions are part of the standard of care for patients with leukemia. This study evaluates two transfusion strategies: one that maintains hemoglobin levels above the standard-of-care threshold, reflecting current routine practice; and another that maintains hemoglobin levels above 110 g/L, which is closer to the normal hemoglobin range. The normal hemoglobin range is 120-160 g/L for females and 140-180 g/L for males. Raising hemoglobin levels closer to normal values may reduce bleeding risk.